The present invention relates to counterbalance assemblies, and more particularly to a mechanical counterbalancing assembly for closure devices such as overhead sliding doors.
Overhead sliding doors are desirable for use in passenger aircraft for a variety of reasons, including ease of manufacture, ease of assembly, a minimum number of uncomplicated operating parts, and stowage in a remote location over the door opening when in use. Doors of this type are conventionally power driven. However, to reduce cost, weight, and complication of the door operating mechanism, it is desirable to eliminate the necessity for the power drive feature and to provide an improved counterbalancing mechanism that will provide the capability of readily opening and closing the door manually.
The weight of the door to be counterbalanced will vary, based on customer preferences in door design and because emergency escape equipment, normally attached to the door, may be unattached when the door must be closed or opened. Therefore, another object of the present invention is to provide a counterbalance assembly that can easily and economically accommodate a range of door weights. A further object of the present invention is to provide mechanism that will prevent the door from opening too fast if the counterbalance assembly is assisted in its function or when the door is opened in a emergency free of the weight of the escape equipment.
Further objects of the present invention are to provide a counterbalance assembly that will generate little internal friction, that will be light, that will be relatively simple and inexpensive to manufacture, and that will be compact as practicable.